1. Field of the Invention
This invention relates to a stethoscope, more particularly to a stethoscope which has a pair of binaural tubes that can apply an optimum clamping force onto the user's ears and which produces a minimum sound distortion when in use.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional stethoscope is shown to comprise a pair of binaural tubes 10, a Y-shaped rubber tube 13 having a first tube section 16 and two second tube sections 14 connected to the first tube section 16, and a U-shaped resilient member 12. The first tube section 16 has a lower end which is connected to a chest piece (not shown). Each of the second tube sections 14 has an upper end which is connected to a lower end of a respective one of the binaural tubes 10. The U-shaped resilient member 12 has two upper ends engaging respectively the binaural tubes 10 in order to apply a clamping force onto the user's ears when the stethoscope is in use.
Some of the drawbacks of the conventional stethoscope are as follows:
1. The clamping force is hardly maintained at a constant, proper amount after the stethoscope has been in use for a period of time. Therefore, the user must adjust the clamping force several times by bending the U-shaped resilient member 12. Control of the adjustment of the clamping force applied by the U-shaped resilient member 12 to an optimum amount is difficult to conduct. If the clamping force is too large, the user's ears may feel uncomfortable. On the contrary, if the clamping force is too small, the binaural tubes 10 are likely to slip from the user's ears while the stethoscope is in use.
2. The sound is transmitted from the chest piece to the user's ears through the rubber tube 13, which produces high sound distortion.
3. The sharp edges of the U-shaped resilient member 12 may injure the user's hands.
Referring to FIGS. 3 and 4, another conventional stethoscope is shown to comprise a pair of binaural tubes 11, a Y-shaped rubber tube 18 and a U-shaped resilient member 17. The structures of the binaural tube 11, the rubber tube 18 and the U-shaped resilient member 17 are similar to those of the aforementioned conventional stethoscope. However, the U-shaped resilient member 17 is disposed within the rubber tube 18 in order to protect the user from being injured by the U-shaped resilient member 17. Since the U-shaped resilient member 17 will reduce the sound transmission efficiency, a sound divider 19 is mounted in the intersection point of the rubber tube 17 in order to enhance the sound transmission efficiency. However, sound distortion still occurs during the transmission of sound in the stethoscope. In addition, the problem of adjustment of the clamping force of the binaural tubes 11 still exists in this stethoscope.